VIDEO: CH. 20 Functional Groups with Double Bonds

Overview

This lecture covers functional groups with double bonds, focusing on the structures, properties, and naming rules for aldehydes and ketones.

An aldehyde has a carbonyl group bonded to at least one hydrogen and one R group (carbon-containing group).
Basic structure: R-CHO; example: formaldehyde (H-CHO).
Aldehydes often have strong, distinctive aromas (e.g., cinnamon, almond scents).
To name aldehydes, replace the -e of the alkane with -al (e.g., ethanal for a two-carbon aldehyde).
The carbonyl carbon in aldehydes is always carbon 1 and included in parent chain numbering.
Example: CH3CH2CHO is propanal; 2-methylpropanal is named by numbering from the carbonyl carbon.

A ketone has a carbonyl group bonded to two R groups (no hydrogen directly attached).
Basic structure: RCOR'; example: acetone (nail polish remover).
To name ketones, replace the -e of the alkane with -one and give the position number of the carbonyl group (e.g., 2-butanone).
Number the chain so the carbonyl carbon gets the lowest possible number.
If substituents are present, indicate their position and name (e.g., 3-methyl-2-butanone).

For both groups, use prefix (substituents), root (longest parent chain), and suffix (-al for aldehydes, -one for ketones).
Always identify and number the carbonyl group for correct naming.

Carbonyl group — a carbon atom double-bonded to an oxygen atom (C=O).
Aldehyde — compound with a carbonyl group bonded to at least one hydrogen and one R group.
Ketone — compound with a carbonyl group bonded to two R groups.
R group — a generic carbon-containing group or substituent.
Suffix -al — indicates an aldehyde in IUPAC naming.
Suffix -one — indicates a ketone in IUPAC naming.